1. Field of the Invention
The present invention relates to a configuration control system, more particularly, it relates to a control system for changing the system configuration of a data processing system. The configuration control system according to the present invention is advantageous for use in a large scale and complicated data processing system constituted by , for example, a plurality of clusters and at least one global storage unit, each cluster having a channel processing unit, at least one central processing unit, at least one main storage unit, a memory control unit and a service processor, and each of the global storage units supporting in common these plural clusters. Usually, the above type data processing system is divided into a current system and a stand-by system for achieving a high reliability and high speed processing in conjunction with each of the global storage units.
2. Description of the Related Art
The management of the system configuration of the data processing system is usually performed by each of the configuration control registers provided in the memory control unit and the global storage unit. That is, each of the units constituting the cluster is connected to or disconnected from other units by turning ON/OFF ("1" or "0") a specific bit of the configuration control register.
In this conventional data processing system, the system configuration is relatively small scale. Further, a "non-stop system" (a "non-stop system" is one in which the operation of the system is not stopped when changing the system configuration) is not usually required by an end user. Accordingly, the configuration is only changed by the service processor using a general scan-in/out function usually provided in data processing systems. In this case, the central processing unit sends a command to change the configuration to the service processor and the service processor performs the above steps. Therefore, it is not necessary to add new configuration changing hardware to the data processing unit, and accordingly, it is possible to economically perform the configuration change.
In this case, the configuration control resister is operated by a clock signal different from the clock signal used to operate the cluster. Accordingly, the whole system must be temporarily stopped to ensure normal operation of the cluster.
Recent data processing systems have become larger scale; for example, a typical large scale data processing system constitutes a plurality of clusters with global storage units for controlling each of the clusters as explained above. In this large scale system, any one service processor can change the configuration of the whole system, and in this case, the whole system is stopped for a considerable length of time. As a result, a "non-stop system" enabling a change of the configuration without stopping the system is now required in large scale data processing systems to achieve a high speed control when changing a configuration.